Re: Wiping an unencrypted SSD in preparation for encryption

[rhkramer@gmail.com]

On Friday, June 11, 2021 02:49:03 AM Reco wrote:
> On Thu, Jun 10, 2021 at 11:43:12PM -0700, David Christensen wrote:
> > I don't bother with the 'discard' option in /etc/fstab, but perhaps I
> > should.  The fstab(5) and mount(8) manual pages are unclear if
> > 'discard' applies to swap or ext4.
> 
> swapon(8):
> 
>    -d, --discard[=policy]
> 	  Enable  swap  discards ... The /etc/fstab mount options discard,
> discard=once, or discard=pages may also be used to enable discard flags.

So, I'm not clear on what happens if you don't use the discard option.  I 
assume that the data in swap is swapped back (written back) to the proper 
location in RAM before reusing the swap space, which would be unnecessary if 
the 


       -d, --discard
              Discard freed swap pages before they are reused, if the swap 
device supports the discard or trim operation.  This may improve performance 
on some  Solid  State  Devices, but  often  it  does  not.   The  /etc/fstab 
mount option discard may be also used to enable discard flag.